Stephanie ate 5 slices of pie. Luis ate 5 slices. If Stephanie ate $\dfrac{5}{15}$ of the pie, what fraction of the pie is remaining?
Answer: If 5 slices represent $\dfrac{5}{15}$ of the pie, there must have been a total of 15 slices. $\text{fraction of pie remaining} = \dfrac{\text{number of slices remaining}}{\text{number of slices total}}$ Together they ate 10 slices, which leaves 5 out of 15 slices remaining. There is $\dfrac{5}{15}$ of the pie remaining.